318 OPERATIONS SUBSIDIARY TO INDUCTION. 



manner, from the names of the simple substances 

 which enter into it as elements. This was done, most 

 skilfully and successfully, by the French chemists. 

 The only thing left unexpressed by them was the 

 exact proportion in which the elements were com- 

 bined ; and even this, since the establishment of the 

 atomic theory, it has been found possible to express 

 by a simple adaptation of their phraseology. 



But where the characters which must be taken into 

 consideration in order sufficiently to designate the 

 Kind, are too numerous to be all signified in the deri- 

 vation of the name, and where no one of them is of 

 such preponderant importance as to justify its being 

 singled out to be so indicated, we may avail ourselves 

 of a subsidiary resource. Though we cannot indicate 

 the distinctive properties of the kind, we may indicate 

 its nearest natural affinities, by incorporating into its 

 name the name of the proximate natural group of 

 which it is one of the species. On this principle is 

 founded the admirable binary nomenclature of botany 

 and zoology. In this nomenclature the name of every 

 species consists of the name of the genus, or natural 

 group next above it, with a word added to distinguish 

 the particular species. This last portion of the com- 

 pound name is sometimes taken from some one of the 

 peculiarities in which that species differs from others 

 of the genus; as Clematis integrifolia , Potentilla alba, 

 Viola palustris, Artemisia vulgaris; sometimes from a 

 circumstance of a historical nature, as Narcissus poe- 

 ticus, Potentilla tormentilla (indicating that the plant 

 was formerly known by the latter name), Exacum 

 Candollii (from the fact that De Candolle was its first 

 discoverer) ; and sometimes the word is purely conven- 

 tional, as Thlaspi bursa-vastoris, Ranunculus thora: it 

 is of little consequence # hich ; since the second, or as 



